In recent years, with a rapid development of semiconductor technology, various miniaturized and thinned electronic products have been designed. In a product applied in electric-acoustic field, a microphone is adopted to convert a sound wave into an electrical signal. Many electronic products available on the market are provided with an MEMS (Micro-Electro-Mechanical) microphone. Compared with a common electret microphone (ECM), the MEMS microphone has better heat resistance, shock resistance, and radio frequency immunity.
The MEMS microphone is a miniature microphone manufactured by etching a pressure sensing diaphragm on a semiconductor using a microelectronics mechanical system process. The MEMS microphone is widely applied to a cellphone, a headphone, a notebook computer, a camera and a vehicle. Due to a requirement in compatibility between the MEMS microphone and a Complementary Metal-Oxide-Semiconductor Transistor (CMOS) and a further reduction in the size of the MEMS microphone, a packaging structure of the MEMS microphone has become a focus of recent research. In the conventional art, a CMOS circuit and the MEMS microphone are generally manufactured separately and then are disposed on a base, with the CMOS circuit and the MEMS microphone being connected via a lead wire.
Transmission of an electrical signal between a microphone chip and a CMOS circuit chip is necessary for processing the electrical signal outputted from the microphone chip. Thus, the microphone chip and the CMOS circuit chip are packaged in a system level to form the MEMES microphone.
In a conventional method for manufacturing the MEMS microphone, processes for the manufacturing the microphone chip and the CMOS circuit chip have great differences, and it is difficult to realize monolithic integration. In a case that the CMOS circuit and the microphone are manufactured on a single substrate, the presence of the microphone structure negatively impacts the manufacturing of the CMOS circuit, and the presence of the CMOS circuit makes it difficult to manufacture the microphone structure with a small size. Therefore, it is a complex manufacture procedure to manufacture the CMOS circuit and the microphone structure on a single substrate, and the formed device has a large size, resulting in increased manufacturing cost.
In manufacturing an integrated microphone structure and a CMOS circuit on a single substrate, if components of the microphone structure were manufactured before the CMOS circuit, the substrate is affected by the process for manufacturing the microphone structure, thereby reducing yield of manufacturing the CMOS circuit. If the CMOS circuit were manufactured before the components of the microphone structure, the presence of the CMOS circuit posts great limitations on the selection of materials and process temperatures of the microphone structure, thereby severely degrading the performance of the microphone structure.
Thus, it is urgently needed a method and a structure for effectively integrating the microphone structure and the CMOS circuit.